The present invention relates to a microtome for producing thin sections for microscopy.
Microtomes are increasingly being equipped with motor units in order to implement the necessary displacement between the sectioning knife and specimen holder, and for the oscillating motion between sectioning knife and specimen holder to generate the thin sections. In this context, a person actuates an operating unit whose signals are processed by a control system so that a first motor unit executes a relative motion between a sectioning knife and a specimen holder in order to bring the two closer to or farther away from one another. The movement speed can be relatively high for the coarse drive mode, until contact takes place between the sectioning knife and a specimen on the specimen holder. When the sectioning knife is in contact with the specimen, the advance must be decreased or halted in order not to destroy the specimen, for example a biological tissue sample. The advance rate for each sectioning motion for generation of the thin sections is often on the order of micrometers, and is thus much lower than for the aforementioned coarse drive mode. This coarse drive mode is usually implemented in different speed increments depending on the distance of the specimen from the sectioning knife. The closer the sectioning knife is to the specimen, the more slowly the further approach should occur so as not to damage the specimen. When controlling this approach, the operator should, if possible, not turn his or her gaze away from the specimen. Operation of the various control parameters, such as coarse drive, fine positioning, and adjustment of the advance rate, with a single hand would be advantageous in this context.
EP 0 920 613 B1 discloses a rotating disc microtome in which at least one specimen holder is mounted on a disc. The oscillating motion between the sectioning knife and specimen holder is produced by rotation of the disc. Relative displacement of the sectioning knife with respect to the specimen holder can be accomplished with a variety of actions: for example, the sectioning knife can be moved horizontally along a base bed, the disc can be moved along the base bed or along the oblique rotation axis of the disc, the disc can be moved vertically on the base bed, and/or the sectioning knife can be moved vertically with the disc placed obliquely.
DE 199 11 163 C1 discloses a microtome in which the displacement of a handwheel is converted, with the aid of electronic positioning elements, into electrical signals that enable control in such a way that a motor unit executes a relative motion between the specimen holder and sectioning knife.